Suspension set-up advice please.

[A900ss]

I've recently replaced all my coilovers on my car and am occasionally bottoming out at the rear a little and am looking for advice.

FYI the car is a tvr Chimaera that has a factory spring rate of Front 277.5 lbs/in and rear 217 to 342.5 lbs/in progressive spring rate.

These have been replaced by a standard set of aftermarket coilovers that are adjustable for rebound and have 400lbs springs on the Front and 325lbs springs on the Rear. Constant, not progressive rate.

I didn't know that the originals were progressive springs when I bought the replacements but was lead to believe that they were stiffer than the originals. In all but the most extreme circumstances, this is true.

However with the rears bottoming out occasionally I'm looking for advice.

I guess that upping the rebound will have no difference whatsoever as it is the compression damping that needs to be stiffened. I am currently on 9 clicks out of a max of 13 at the rear (and 7 out of 13 at the front).

I could put more ride height in to the springs as they are running slightly lower than original. This is done by rotating the collar underneath the spring but I don't think this is adding any preload as it will already have taken up the slack (is my thinking correct?).

Another option is to change the springs at the rear from 325‘s to 350/375/400.

I think the rear spring rate is a bit too soft for my driving style (Sunday toy, quite quick, bumpy/twisty B roads) as when I pull out to overtake and floor it at the same time, it feels like the car has a bit or 'torque steer' from the rear and I'd like to dial that out if possible.

Thoughts from people who know more than I do are most welcome.

[A900ss]

PS - each time I've bottomed out, I've been 2 up whereas I normally drive solo.

[PaulKemp]

If your max spring rate was 342 and now your running 325 there's your answer
You need more than 342 to make a difference
Dampers damp the springs not replace them ultimately your springs will coil bind if to weak

[b2hbm]

hmm, I think I'd go for the springs as well, you've already got the dampers wound up by the sounds of it.

Raising the spring support platform will increase pre-load on the spring and also ride height, so it might get you out of the immediate problem of grounding. The downside is that you might have to raise it so much that either the spring becomes coil-bound in use or the road holding goes to pot with an excessively high rear ride height.

I don't know enough about TVRs to comment on the spring rate options you have or what is the best balance for your new front spring rates. Gut feel says it should at least be as high as your OEM setup.

edit to add - if the car feels unstable with strong acceleration I'd be looking at wear in bushes, driveshaft and linkages first ?

Edited by b2hbm on Tuesday 29th October 21:46